Pulsed Laser Deposition of Aluminum Nitride Films: Correlation between Mechanical, Optical, and Structural Properties

Abstract

Aluminum nitride (AlN) films were synthesized onto Si(100) substrates by pulsed laser deposition (PLD) in vacuum or nitrogen, at 0.1, 1, 5, or 10 Pa, and substrate temperatures ranging from RT to 800 °C. The laser parameters were set at: incident laser fluence of 3–10 J/cm2 and laser pulse repetition frequency of 3, 10, or 40 Hz, respectively. The films’ hardness was investigated by depth-sensing nanoindentation. The optical properties were studied by FTIR spectroscopy and UV-near IR ellipsometry. Hardness values within the range of 22–30 GPa and Young’s modulus values of 230–280 GPa have been inferred. These values were determined by the AlN film structure that consisted of nanocrystallite grains, strongly dependent on the deposition parameters. The values of optical constants, superior to amorphous AlN, support the presence of crystallites in the amorphous film matrix. They were visualized by TEM and evidenced by FTIR spectroscopy. The characteristic Reststrahlen band of the h-AlN lattice with component lines arising from IR active phonon vibrational modes in AlN nanocrystallites was well detectable within the spectral range of 950–500 cm−1. Control X-ray diffraction and atomic force microscopy data were introduced and discussed. All measurements delivered congruent results and have clearly shown a correlation between the films’ structure and the mechanical and optical properties dependent on the experimental conditions.

AlN formation by an Al/GaN substitution reaction

“…Thus, the formation of N 2 gas may cause the deviation of the TG curve of the Al/GaN sample from the baseline observed in Fig. 2c The overall reaction is given by the sum of reactions (6)- (9) The growth rate of AlN can be controlled by either interfacial reactions or interdiffusion. Assuming the interfacial reaction rates are much faster than interdiffusion, the growth rate is controlled by the diffusion.…”

“…AlN can be grown in two forms: film and bulk. AlN films have been fabricated by various methods, such as metal–organic vapour-phase epitaxy (MOVPE) 4 , 5 , hydride vapour phase epitaxy (HVPE) 6 , 7 , pulsed laser deposition (PLD) 8 , 9 , molecular beam epitaxy (MBE) 10 , 11 , or sputtering 12 , 13 , to improve its crystalline quality, surface area, growth rate, or lower its processing temperature. Annealing techniques have been demonstrated to improve the crystalline quality of AlN films 14 – 16 .…”

Temperature Dependence of Stress and Optical Properties in AlN Films Grown by MOCVD

“…Sapphire is widely used as a substrate of choice for AlN epitaxial growth because of its easy availability and low cost. AlN films have been grown by various methods [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ], such as chemical vapor deposition (CVD), pulsed sputter deposition (PSD), pulsed laser deposition (PLD), molecular beam epitaxy (MBE), reactive magnetron sputtering, hydride vapor phase epitaxy (HVPE), and metal organic chemical vapor deposition (MOCVD). CVD is found to be the most suitable technique in controlling the preferred orientation [ 21 ].…”

Synthesis and Physical Properties of Antiperovskite CuNFe3 Thin Films via Solution Processing for Room Temperature Soft-Magnets

“…Transition-metal nitrides are widely known for their interesting physical properties and potential applications with superconductivity for the electronic device, unusual magnetic properties for the high-density recording materials, excellent electrochemical characteristics for supercapacitors, and high mechanical strength for cutting tools [1][2][3][4][5]. Among the ternary metal nitrides, one of the most widely studied nitrides is a compound with antiperovskite structure.…”